Question

Find the surface area of a wooden cube of side length 30 cm. ​

Answer 1

Surface area of the cube is 5400 cm².

Given data :

One side = 30 cm

We know that a cube has six sides.

Surface area of one side = (30×30) cm² = 900 cm²

Total surface area = (900×6) = 5400 cm² (answer)

Answer 2

$</p><p></p><p> </p><p>It is given a cuboid having dimension,</p><p></p><p>length, l = 7 cm</p><p></p><p>breadth, b = 4 cm</p><p></p><p>height, h = 3 cm</p><p></p><p>Now, We know that,</p><p></p><p>surface area of cuboid = 2(lb +bh +hl)</p><p></p><p>So, the surface area ,</p><p></p><p>S1 = 2( 7×4 + 4×3 + 3×7 )</p><p></p><p>=> S1 = 2( 28 + 12 + 21)</p><p></p><p>=> S1 = 2 × 51</p><p></p><p>\bold{= > S1 = 102{cm}^{2}}=>S1=102cm </p><p>2</p><p> </p><p></p><p>Now, after doubling the dimension,</p><p></p><p>we have , new dimensions,</p><p></p><p>l' = 7×2 = 14 cm</p><p></p><p>b' = 4×2 = 8 cm</p><p></p><p>h' = 3×2 = 6 cm</p><p></p><p>So,the new surface area,</p><p></p><p>S2 = 2(14×8 + 8×6 + 14×6 )</p><p></p><p>=> S2 = 2 × 244</p><p></p><p>\</p><p>.</p><p></p><p>= > S2 = 488{cm}^{2}}=>S2=488cm </p><p>2</p><p> </p><p></p><p>Clearly, we can see that</p><p></p><p>2S1 ≠ S2</p><p>Hence, it is wrong assumption.$